Connect words with images and find the name of the whatchamacallit on the tip of your tongue with Merriam-Webster's Visual Dictionary. The site is sort of like a reverse 20 questions (because you don't know the answer), starting at one of 15 visual themes and narrowing down your search image by image to find the name of exactly what you're looking for. Alternatively, you could try looking up a word by its definition with the Reverse Dictionary.